Cytomegalovirus (CMV) Tests

What are cytomegalovirus (CMV) tests?

Cytomegalovirus (CMV) tests check for signs of CMV in your blood, sputum, or other body fluids. CMV is a virus in the herpes family. Other types of herpes viruses include the viruses that cause chickenpox and mononucleosis (mono).

CMV is a common virus that infects people of all ages. Most people have been exposed to CMV during childhood. Once you get a CMV infection, the virus stays in your body for the rest of your life. Most of the time, the virus stays dormant (inactive). However, it can become active again (reactivated) in certain situations, such as when you are under a lot of stress or if you have an immune system problem.

If the CMV virus is active, it can be spread through body fluids such as:

• Saliva
• Urine
• Blood
• Tears
• Semen
• Breast milk

Most healthy people don't have any signs or symptoms of a CMV infection. They usually aren't even aware they have one. But sometimes a CMV infection may cause mild, flu-like symptoms in healthy people. These symptoms will often go away within a few weeks.

Your provider can check for CMV by testing for:

• Antibodies that respond to the CMV virus. An antibody is a protein that your immune system makes to attack germs and other foreign substances in your body.
• Genetic material (DNA) of the CMV virus. This is called a polymerase chain reaction (PCR) test.

Other names: CMV IgG and IgM, cytomegalovirus antibody, PCR Test

What are they used for?

CMV tests only help to diagnose a current, reactivated, or past CMV infection in people at risk of health complications. You may be at higher risk if you:

• Have a weakened immune system due to conditions such as HIV or cancer. This can lead to health complications such as eye damage, inflammation in the lungs or digestive tract, and brain swelling.
• Are pregnant and have an active CMV infection. This is because you can pass the virus to your fetus. In severe cases, this could lead to the loss of the fetus through a miscarriage or stillbirth.
• Recently received an organ transplant. This is because an active CMV infection can cause your body to reject the new organ.

Infants are also at higher risk of health problems from CMV if they:

• Got a CMV infection before they were born (also known as congenital CMV). Most babies don't have health problems from the virus, but if they do, they may experience long-term hearing loss. Congenital CMV can also cause vision problems, intellectual disabilities, and other serious disorders.
• Had a very low birth weight or were born premature. This can lead to a CMV infection during childbirth or from breastfeeding. That's because babies who have a low birth weight or are born premature are less able than healthy babies to fight the infection.

CMV testing can help those at risk of complications get the treatment they need. While there is no cure for CMV, antiviral medicines and other treatments may reduce both your symptoms and the chance for future health complications.

Antibody testing may also be used to help your provider see if a CMV infection is active or inactive (latent). To do this, they may need to test your antibody levels again, three months after they test them for the first time.

Why do I need a CMV test?

You may need testing if you have a weakened immune system or are pregnant and have the following symptoms:

• Swollen lymph nodes (“swollen glands”)
• Sore throat
• Fever
• Fatigue
• Weakness
• Muscle aches
• Headache

Your baby may need this test if they have the following symptoms:

• Jaundice, a condition that causes your skin and eyes to turn yellow
• Low birth weight
• Small head
• Hearing and/or vision problems
• Seizures
• Rash

What happens during a CMV test?

There are several types of CMV tests. For adults, these include:

• Blood tests
• Cerebrospinal fluid (CSF) analysis (spinal tap)
• Sputum tests (sputum is thick mucus made in your lungs)
• Biopsies
• Amniocentesis

For newborns, test types include:

• Infant saliva tests
• Infant urine tests

For a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes. This is the most common way to test adults for CMV.

For a cerebrospinal fluid (CSF) test, a provider will do a procedure called a spinal tap, also known as a lumbar puncture. A spinal tap is usually done in a hospital. During the procedure:

• You will lie on your side or sit on an exam table.
• A provider will clean your back and inject an anesthetic into your skin, so you won't feel pain during the procedure. Your provider may put a numbing cream on your back before this injection.
• When the area on your back is completely numb, your provider will insert a thin, hollow needle between two vertebrae in your lower spine. Vertebrae are the small backbones that make up your spine.
• Your provider will withdraw a small amount of cerebrospinal fluid for testing. This will take about five minutes.
• You'll need to stay very still while the fluid is being withdrawn.
• Your provider may ask you to lie on your back for an hour or two after the procedure. This may prevent you from getting a headache afterward.

For a sputum test:

• You may be asked to rinse your mouth out with water before the sample is taken.
• Your provider will ask you to breathe deeply and then cough deeply into a special cup.
• Your provider may tap you on the chest to help loosen sputum from your lungs.
• If you have trouble coughing up enough sputum, your provider may ask you to breathe in a salty mist to help you cough more deeply.
• If you still can't cough up enough sputum, your provider may perform a procedure called a bronchoscopy. In this procedure, you'll first get a medicine to help you relax, and then a numbing medicine so you won't feel any pain.
• Then a camera attached to a thin, lighted tube will be put through your mouth or nose and into your airway. This helps your provider see the inside of your lungs and airway.
• Your provider will collect a sample from your airway using a small brush or suction.

During a biopsy, your provider will remove a small sample of tissue for testing. There are many ways to do a biopsy, though they aren't done as often as other types of tests for CMV. In general, a biopsy may be done using:

• A hollow needle inserted through your skin. Imaging tests, such as ultrasound, may be used to guide the needle:
  • A fine needle aspiration biopsy uses a very thin needle to remove a sample of cells and/or fluid.
  • A core needle biopsy uses a larger needle to remove a sample.

An amniocentesis is done during pregnancy to see if the fetus has been infected with CMV.

• You'll lie on your back on an exam table.
• Your provider will apply a gel to your belly.
• Your provider will move an ultrasound wand-like device, called a transducer, on your belly. Ultrasound uses sound waves to show the position of the fetus and placenta so your provider can see where to take a sample of amniotic fluid.
• Your provider will clean your belly.
• Your provider will insert a thin needle into your belly, withdraw a small amount of amniotic fluid, and then remove the needle.
• When the sample is removed, your provider will check the fetal heartbeat with the ultrasound.
• The sample is sent to a lab for testing. Results may take from a few days to a few weeks.

Newborns are usually given a saliva or urine test.

During an infant saliva test:

A saliva specimen is collected within three weeks of your baby's birth and at least an hour after breastfeeding.

• Your provider will insert a sterile swab into your baby's cheek and swirl for several seconds.
• The swab will be placed in a special solution for testing.

During an infant urine test:

• You will be given a special plastic bag that will fit over your baby's genital area.
• You will place a diaper over the bag.
• After your baby has urinated, you will remove the bag from the diaper and empty the urine into a container given to you by your provider.

Will I need to do anything to prepare for the test?

You don't need any special preparations for a blood or sputum test. There are also no preparations needed for an infant saliva or urine test.

You may need to empty your bladder before a spinal tap.

You may be asked to fast (not eat or drink) for several hours before a biopsy.

For an amniocentesis, you may be asked to not urinate (pee) before the test to make sure you have a full bladder. This helps move the uterus into a better position for the test. In later pregnancy, you need to have an empty bladder for the test.

Your provider or your child's provider will let you know if you need to make any other preparations.

Are there any risks to the test?

There are no known risks to having a sputum test, infant saliva test, or infant urine test.

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There is very little risk to having a spinal tap. You may feel a little pinch or pressure when the needle is inserted. After the test, you feel some pain or tenderness in your back or have some bleeding where the needle was inserted. You may also get a headache. The headache may last for several hours or up to a week or more, but your provider may suggest treatment to relieve the pain.

If you had a biopsy, you may have a little bruising, bleeding, or soreness at the biopsy site. This usually goes away after a few days.

If you had amniocentesis, you may have some stinging, pressure, and/or cramping during the test. Afterward, you may have mild discomfort or vaginal bleeding, or a small amount of amniotic fluid may leak from your vagina. The risk of serious complications is extremely low. Your provider will let you know if there are any symptoms that you should tell them about. These may include ongoing vaginal bleeding, amniotic fluid leakage, severe cramping, or a fever.

What do the results mean?

The test result can show whether you have ever had a CMV infection. If your provider used antibody testing, they may also be able to see if your infection is active or inactive.

An infection may be active if:

• You have high levels of IgG and IgM, especially if you also have symptoms of CMV.
• You have high levels of IgM and little or no IgG. Your immune system usually only makes IgM when you first get an infection. So, if you have IgM in your sample, it may mean you have an active CMV infection.
• Your IgG levels are higher three months after the results of the first test. To see if this is the case, your provider will have to test your antibody levels twice, three months apart.

A PCR test can show how much of the CMV virus is present. This helps your provider determine how severe the infection is. High levels with symptoms of CMV may mean you have a severe infection. If the test comes back negative, it does not necessarily mean there is no CMV present in your body. It may only mean that there are very low levels of the virus.

If you have symptoms and/or risk factors, such as an immune system disorder, your provider may do additional tests to help make a diagnosis and create a treatment plan.

If you are pregnant and your amniocentesis shows your fetus has CMV, your child's provider may test and treat your baby soon after birth to help prevent complications.

If you have questions about your results, talk to your provider or your child's provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about CMV testing?

CMV tests are included as part of a TORCH panel, a group of blood tests used to screen newborns and sometimes during pregnancy for the following infections:

• Toxoplasmosis
• Rubella
• Cytomegalovirus
• Herpes simplex virus

These infections can cause birth defects if a mother gets any of these infections during pregnancy. Early diagnosis and treatment may help prevent a baby from getting a serious health problem.

You can't eliminate your risk for CMV, but you can lower your chance of getting infected or spreading the infection by:

• Not sharing food or dishes with a child or putting their pacifier in your mouth.
• Washing your hands well after changing a diaper.
• Wearing gloves and washing your hands well if you are caring for someone who is sick and have contact with their body fluids.
• Using latex condoms correctly every time you have sex. If you or your partner is allergic to latex, you can use polyurethane condoms.